This invention relates to an improved shipping pallet of unitary construction, and to an improved packaging container comprising one each such pallet as top and bottom thereof in combination with a peripheral sleeve forming load-bearing walls and a plurality of strapping bands, suitable for but not limited to the packaging, storage and transport of yarn.
At the present time wooden pallets are widely used to form packaging containers for transporting "cheeses", "bobbins" or "cones" of yarn from a yarn manufacturing or storage facility to a yarn utilization plant, such containers typically also including open wooden sides and an open top, all held together by bailing wire. Such wooden pallets and containers are undesirably heavy but of varying weight, do not completely enclose the yarn to provide desired protection against weather, pilferage, vandalism, soiling and other damage, are susceptible to breakage and other deterioration such as splintering, and have a limited useful life. Further, when such containers are stacked for storage or transport, for example--three or four high, they frequently shift dangerously one with respect to the other, since neither pallet nor container provides adequate means for preventing such relative movement. When such containers are returned empty for re-use, they take up as much space as when loaded, unless they are disassembled. Disassembly is costly, time consuming, and potentially hazardous to employees. Reassembly via bailing wire and so forth is equally time consuming, costly, and potentially hazardous.
In order to overcome these deficiencies of wooden pallets and the containers formed therewith, packaging schemes employing unitary plastic pallets have been devised. In some of these plastic pallet arrangements, exemplified by U.S. Pat. Nos. 3,524,415 to Heiman, 3,526,195 to Maryonovich, and 4,000,704 to Griffin, the package is sandwiched between a top and bottom held together by conventional banding, but without load-bearing side walls, and wherein the yarn "cones" or the like as such bear and transmit the load imposed by stacked containers from one container to the next. Other references of interest are U.S. Pat. Nos. 3,187,691; 3,346,137 and 3,696,761.
The pallet configuration shown in the Heiman patent is self-nesting for unloaded transport or storage as shown in FIG. 2 thereof, self-interlocks with a particularly formed plastic shipping lid as shown in FIG. 1 thereof to prevent shifting while stacked, and accommodates four-way fork lift entry. However, the Heiman pallet has six feet disposed along two opposite edges thereof, with no intermediate support, and therefor has poor load-bearing characteristics. Further, the upper shipping lid cover of the Heiman package necessarily has a different configuration than the supporting pallet at the bottom of the package, and the ridges formed therein for engaging the pallet feet to resist shifting are shallow and subject to disengagement when misaligned or set slightly ajar. As aforesaid, the package formed using such pallet and lid has no load-bearing side wall members, but rather depends on the packaged payload to bear and transmit the weight of stacked containers.
Maryonovich discloses an improvement over the Heiman arrangement, in that a pallet identical to that forming the package bottom may, when inverted, serve to form the package top, with the payload being sandwiched therebetween, and secured by strapping bands. Here again, no provision is made for load-bearing wall members, and the payload itself is relied upon to bear and transmit the weight of stacked containers. Unloaded pallets are nestable for storage or transport in a single orientation only. Adjacent each of the nine pallet feet, which are spaced for four-way fork lift entry, is a socket formed by and within a minimal network of reinforcing ribs. The sockets of an inverted pallet, acting as a top, mate with and receive therewithin the feet of a pallet acting as a bottom of the next higher package in the stack. Such stackability is, however, available in a single orientation only, and indicia would be required for ready location of proper orientation. The nine foot/socket combinations as such transmit the entire vertical load from pallet to pallet, and each mating pair will tend to jam and distort. Moreover, the socket bottoms will tend to be weak, and the dislocations within the minimal reinforcing rib network represented by the sockets will weaken the entire pallet and promote excess flexure under load.
Griffin discloses an alternative to the Maryonovich arrangement, wherein an identical pallet structure can as well be employed both as the supporting pallet and as the top lid, with the payload sandwiched therebetween and secured by banding straps. There being no provision for load-bearing side wall members, the payload itself is relied upon to bear and transmit the weight of stacked packages. The unloaded pallet is also self-nesting for transport or storage as shown in FIG. 9 thereof, and also self-interlocking with a suitably oriented mutually inverted pallet to facilitate stacking while tending to prevent relative shifting. Griffin employs a pallet structure having nine feet, with each foot having a bottom featuring alternating male and female "undulations" or reinforcing ribs. Such undulations are oriented in a "herringbone" pattern so that (as best shown in FIG. 1 thereof) inversion of the pallet in a certain single orientation generates a similarly directed but phase-shifted "herringbone" pattern which interlocks with that of the upside right pallet and wherein the respective female undulations fit together with counterpart male undulations, and vice versa. The Griffin pallet, however, cannot in its principal embodiment accommodate four-way fork lift entry, and in its alternative embodiment would be unable to accommodate such large loads as is asserted therein. It is likewise both nestable and stackable only in a single orientation, thus necessitating the employment of indicia for proper orientation location. The Griffin pallet is stronger than that of Maryonovich, and is thus an improvement thereover. However, Griffin's "herringbone" undulations are shallow, and tend to disengage under misalignment, thus permitting shifting. Said misalignment would be frequently encountered because of the complexity of the "herringbone" pattern, which complexity requires great precision and skill from the fork lift operator attempting to stack packages. Further, such "undulations" as such form the entire vertical support means, and will have some tendency to jam together or otherwise distort under load.
Accordingly, an object of the present invention is to provide an improved unitary shipping pallet which can accommodate four-way fork lift entry, is self-nesting without the need to refer to orientation indicia on the pallets, and which provides increased strength.
A further object of the present invention is to provide an improved unitary shipping pallet with a plurality of foot means so disposed as to mate with an identical inverted pallet in stacked relationship, without resort to orientation indicia, wherein certain portions of said foot means provide vertical-load-bearing support, when engaged with corresponding portions of the foot means of the inverted pallet, and other portions thereof engage in shift prevention relationship with corresponding foot means of said inverted pallet.
A still further object of the present invention is to provide a nestable, stackable shipping pallet wherein the foot means thereof, when mating with the foot means of an inverted pallet in stacked relationship, are so configured as to prevent or minimize foot distortion under load, and to prevent or minimize foot means to foot means jamming due to pallet flexure when under load.
Another object of the present invention is to provide an improved shipping container wherein one said improved pallet serves as the bottom thereof, and an inverted identical pallet serves as top thereof, and wherein vertical-load-bearing walls on each side thereof are provided in the form of a peripheral sleeve, said sleeve mating with a peripheral groove formed in each said pallet by a peripheral rim thereof, said container being secured by strapping bands.
Yet another object of the present invention is to provide an improved shipping container as aforesaid wherein several such containers may be stacked one on top of the other with ease and without requiring significant precision and skill from a fork lift operator, but wherein there is considerably improved stability within a stack of such containers provided by the aforesaid shift-resisting interengagement of the foot means of the respectively adjacent pairs of inverted top pallets and upside right bottom pallets.